The tire for use in the large-sized construction machine or mining machine differs in rigidity from a tire for use in a passenger car, so that the tire for use in the large-sized construction machine or mining machine does not fit into a single-piece rim on many occasions. For this reason, a multi-piece rim is often used in the large-sized construction machine or mining machine.
In FIG. 19, there is shown a construction of such a multi-piece rim. In FIG. 19, a multi-piece rim 100J has a rim base 1, a side ring 2 provided on the right and left sides of a tire, respectively, a bead seat band 3 and a lock ring 4. An end of the rim base 1, on a side thereof, adjacent the lock ring 4, (the right-side end of the rim base 1, in FIG. 19) is called a gutter band 11. A back flange 12 is formed at an end of the rim base 1, on the left side thereof. Further, in FIG. 19, a construction for fitting the multi-piece rim to a side of the tire, adjacent to the construction machine or the mining machine, (to a hub) is not illustrated.
In FIG. 19, when air is pumped into a tire 6, and air pressure in the tire 6 rises, the tire is inflated in both the right and left directions FIG. 19, inducing the respective side rings 2 on the left and right sides of the tire, in FIG. 19, to move in the right and left directions, respectively, whereupon the bead seat band 3 moves in the direction of the arrow Y.
The lock ring 4 is fitted into a groove 11a formed in the gutter band 11, and the gutter band 11 is formed integrally with the rim base 1. Accordingly, the lock ring 4 restricts movement of the side ring 2, and the bead seat band 3, provided on the right side, toward the right-hand side in FIG. 19.
FIG. 20 shows the lock ring 4 formed as a single component (single piece). The lock ring 4 in a single piece has elasticity, particularly, elastic repulsion force acting in the direction of contraction occurring in the direction of the arrow R in FIG. 20 (inwardly in the radial direction), and a break 4s is formed at one spot thereof. However, with the lock ring 4 in a single piece state, that is, when it is not fitted to a rim, the break 4s is closed by the agency of the elastic repulsion force of the lock ring 4.
Unless the lock ring 4 has the elastic repulsion force acting in the direction of contraction occurring inwardly in the radial direction (in the direction of the arrow R in FIG. 20), there is the risk that the lock ring 4 while in use is forced out of the groove 11a (refer to FIG. 19) formed in the gutter band 11. By the agency of the elastic repulsion force causing contraction in the radial direction (in the direction of the arrow R in FIG. 20), the lock ring 4 remains fitted in, and held by the groove 11a. 
Herein, in some large-sized construction machine or mining machine, double tires are provided on a rear wheel side thereof. The double tires are constructed such that a tire and a rim are provided on both the inner and outer sides thereof.
Also, in the case where such a lock ring 4 is to be attached to the multi-piece rim on the outer side or the inner side, it is required that the lock ring is fitted into the groove of the gutter band by causing the lock ring 4 to pass through a rim base of the multi-piece rim on the outer side while holding the lock ring must be maintained a large size in the radial direction thereof (in the direction of the arrow R in FIG. 20) against the urging of elastic repulsion force (the elastic repulsion force causing the contraction in the direction of the arrow R in FIG. 52).
Herein, since there is the case where the lock ring 4 has a mass as large as, for example, on the order of 50 kg, it is extremely difficult to hold the lock ring 4 so heavy in weight while resisting the elastic repulsion force urging the contraction in the radial direction and to dispose the same at a predetermined position, and excessive labor will be required.
As other prior art, there has been proposed, for example, a multi-piece rim disc wheel wherein a rim base, a gutter band, first and second center bands, a disc, and a back flange are joined together by use of complete joint penetration butt welding, capable of coping with an increase in payload (refer to Patent Publication 1).
Such prior art can be useful, however, it does not eliminate a problem associated with mounting/demounting of the lock ring, described as above.    Patent Publication 1: JP-A No. 2000-108603